http://sobereva.com/wfnbbs/index.php
Thu, 21 Mar 2019 17:00:33 +0000FluxBBhttp://sobereva.com/wfnbbs/viewtopic.php?id=169&action=new
All methods that rely on loading coefficients of configuration functions cannot be applied to these methods, such as hole-electron analysis and NTO analysis. However, there are some general excitation state analyses method in Multiwfn, for example, the analysis based on density difference between excited state and ground state (introduced in Section 3.21.3 and illustrated in Section 4.18.3 of the manual). To carry out this analysis, you need to provide wavefunction file containing natural orbitals of CASSCF/CASCI type for ground state and excited state, respectively.]]>Thu, 21 Mar 2019 17:00:33 +0000http://sobereva.com/wfnbbs/viewtopic.php?id=169&action=newhttp://sobereva.com/wfnbbs/viewtopic.php?id=168&action=new
1 To change color of orbital surface, in the menu bar of GUI, select "Isosur#1 style" - "Set color for face". If you input "1,0,0" and then "0,0,1", then the color of positive and negative phases will be red and blue, respectively.

2 You can click "Show axis" box at right side of the GUI to make the axis invisible.

Calculating ratio of CT and LE using Multwfn is based on the charge difference between EX & GS, right?You suggest to use ADCH charge or Mulliken charge. Is it okay to use q_CT from the output to calculate CT/LE ratio?

My reply

The q_CT mentioned in the example of Section 4.18.3 should not be used in evaluating CT/LE ratio, because this term only reflects the amount of electrons *perturbed* during the excitation, it doesn't directly correspond to the amount of electrons *transferred* from one fragment to another fragment. Commonly, you should use variation of fragment charge (can be evaluated using various atomic charge calculation methods) to evaluate CT/LE ratio. Using the amount of CT evaluated by the IFCT analysis is also completely OK, the IFCT analysis is illustrated in Section 4.18.8.

To avoid confusion about the physical meaning of the qCT, in fact there is a paragraph in Section 3.21.3:The transferred charge qCT is the magnitude of the integral of rho+ and rho− over the whole space.It is important to correctly recognize the physical meaning of this quantity. qCT only corresponds to the total amount of charge whose distribution is perturbed during electron excitation, it does not correspond to net charge transfer from one fragment to another fragment (e.g. from donor group to acceptor group)

I calculated Mulliken atomic charges of an organic small molecule using Psi4. I also need to calculate both the RESP and AM1-BCC charges for the same molecule. Do you know that how I can calculate the RESP and AM1-BCC charges of a molecule with Psi4?

I copy my reply here since the content may be useful for others

You can use my code Multiwfn (http://sobereva.com/multiwfn) to calculate RESP charge, the details of RESP is documented in Section 3.9.16 of Multiwfn manual, related examples are given in Section 4.7.7, you will find using Multiwfn to derive RESP charges is extremely easy. The .fch file generated by PSI4 can be directly use as input file, the way of generating .fch file via PSI4 is explicitly mentioned at begnning of Chapter 4 of Multiwfn manual.

Commonly, RESP works much better than AM1-BCC, the main purpose of the latter is to obtain charges with similar feature and quality as RESP but with evidently lower cost. Since evaluation of RESP charges for small molecule is never expensive, I don't think there is any reason to use AM1-BCC.

Please simply ignore these formal charges, they are assigned artificially and do not make great sense. You only need to properly set total net charge in the quantum chemistry calculation, only the finally obtained atomic charges can relatively faithfully represent actual charge distribution.

]]>Sat, 02 Mar 2019 07:24:20 +0000http://sobereva.com/wfnbbs/viewtopic.php?id=161&action=newhttp://sobereva.com/wfnbbs/viewtopic.php?id=160&action=new
You can try to use CHELPG and MK, if the transition metal charge is still very negative, the reason should be that the ESP fitting method in principle doesn't work well for your systems. In transition metal complexes, the transition metal is often very heavily buried, in this case its fitted charge is numerically unstable (because the fitting center is very far from fitting points) and the result doesn't make great sense. In this case you should employ other kinds of atomic charges instead, such as ADCH, Hirshfeld-I, etc.

Thank you for your speedy reply, I managed to sort the issue out! again really happy with the software.

Kane

]]>Thu, 28 Feb 2019 23:26:02 +0000http://sobereva.com/wfnbbs/viewtopic.php?id=158&action=newhttp://sobereva.com/wfnbbs/viewtopic.php?id=159&action=new
Using M06-2X to evaluate pKa is a good choice. D3 correction should not detectably affect the pKa result, since the influence of D3 for M06-2X calculation is marginal, and present problem has little correlation with weak interaction.

Multiwfn doesn't directly provide a way of predicting pKa, but many quantities that can be calculated by Multiwfn have direct relationship with pKa. For example, atomic charge of the hydrogen, electrostatic potential at the nuclear position of the hydrogen (without contribution from this proton) and so on. My collaborators have published an article Journal of Computational Chemistry 2018, 39, 117–129 to discuss relationship between pKa and a batch of molecular descriptors (many of them can be easily calculated by Multiwfn).

In fact I don't exactly understand what is the central problem in your question. If the functionalized carbon nanotube have multiple sites that can occur deprotonation, you can calculate respective pKa for each site in usual way.

For Mulliken transition charge calculation, is it possible to use charge restraint over a few atoms in Multiwfn just like RESP module for electrostatic potential...? Thanks.

Best,Sayan

Dear Sayan,

No, it is not possible.

Best,

Tian

]]>Fri, 22 Feb 2019 13:55:45 +0000http://sobereva.com/wfnbbs/viewtopic.php?id=156&action=newhttp://sobereva.com/wfnbbs/viewtopic.php?id=157&action=new
I forgot to mention that your .cube file cannot be properly processed by Multiwfn, because only cubic grid is supported by current version of Multiwfn, however the three translation vectors of your cube file are not all parallel to the three Cartesian axes.I intend to extend Multiwfn to make Multiwfn support triclinic grid in the future.]]>Sun, 17 Feb 2019 02:55:46 +0000http://sobereva.com/wfnbbs/viewtopic.php?id=157&action=newhttp://sobereva.com/wfnbbs/viewtopic.php?id=155&action=new
Hello

Please ignore this one. I had to reinstall version 3.6 somehow it became corrupted.